Plating of bones is a time tested principle which has evolved from bridging the fractured bone using round holed plate, wherein normal screws are used to press the plate to the bone for holding the fractured bone together while the bone gets healed. The usage of bone plates had revolutionized the trend towards the surgical approach of bone fractures. However, conventional plates could not produce compression between the fractured bones and also led to compromise of periosteal blood supply.
To overcome the problem associated with the convention plate, dynamic compression plates have been developed with oval holes with a slope. The slope of the hole is inclined at an angle and tightening of a screw-head towards the hole converts the vertical movement of screw-head into horizontal movement of plate thus producing compression between the fractured bones. However, the compression of bones results from friction between bone and undersurface of the plate, which leads to reduction of periosteal blood supply to bone thus weakens and erodes the bone.
Subsequently, limited contact plates had been developed to minimize the contact between plate and bone by providing undercuts to enable limited contact and lower the erosion of bone, however the problem of friction could not be completely eradicated.
The usage of dynamic compression plates and limited contact plates results in friction between plate and bone, hence even a small spot of weakness can defeat the stability. Moreover, the plate may loosen and fail in rigidity, which can also predispose to infection.
Thus to eliminate the above friction phenomena, locking plates have been introduced which are non-contact plates and does not contact the bone underneath once the screw is locked. In such locking plate, threads were provided at holes and heads of screw with matching pitch for achieving non-contact with bones and also providing structural rigidity, strength and stability. On the other hand, the locking plates could not compress the fracture site and nonunion of bones can occur when there is an unreduced fracture.
In order to overcome the problem associated with the prior art, research has been focused towards developing a locking plate which can combine the locking and compression principles to form a single hole pairing both of them in a shape like peanut shell or otherwise. Such type of locking plate with locking screws and compression screws can offer both the locking and compressing of bones and buttressing option all in one. However, it has been observed that the locking screw can only provide non-contact on bone surface, but tightening of the compression screw resulted in contact with bone and also friction between bone and locking plate while compressing.
Therefore there exist a need in the art to develop a method and novel design of locking plate and locking plate unit to overcome the problem associated with the prior art, and also provide exclusive non-contact plate which can achieve locking and compression without friction and contact between bone and plate interface.